life sciences lesson 1 & 2

8/4/2019 Life Sciences Lesson 1 & 2

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Animal Nutrition


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Introduction

Plants are autotrophic and thus theyproduce

their own food.

Without the process so called photosynthesis,

plants can not produce their own food.

This process takes place in chlorophyll

containing plants.


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Primary Producers (autotrophs)

These plants can make

their own food using

Sunlight

Chlorophyll

Water

Carbon dioxide


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Introduction

This is in contrast with heterotrophs

They must obtain their food from other

organisms.

Most heterotrophic organisms have to convert

solid, complex food into soluble state which is

capable of being absorbed into the blood and

transported to all the cells of the body.


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What determines our diet?

Our diet is determined by:

Fashion fashion dictates what we eat as well aswhat we dress in.

Religions different world religions give guidanceon what can or should be eaten. E.g. Pork

Doctor prescription / recommendations.

Moral grounds objections to the killing ofanimals.

Personal health choices.


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Why do we need to eat??


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Carbohydrates and Fats

We need carbohydrates to:Supply energy to the body.

Provide energy (calories)

Lipids (Fats and Oils)

They are Insoluble in water

They Provide HIGH ENERGYLipids provide over twice carbohydrates

energy.


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Proteins

They help in:Growth and repairs of all cells

Development from young to adult

Production of hormones, enzymes and antibodies


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Minerals

In maintaining body process we needvitamins and mineral salts.

They help us in:

Bone development

Teeth development

Chemical process regulation

Nervous system function and also in

Reproduction


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Food

Type

Carbohydrate

Fat

Protein

Sugars

These are types of food that we normallyconsume.But what happens to the food we eat??


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There are 6 main steps that food

travels in animals digestive system.

1. Ingestion:

2. Digestion3. Absorption

4. Translocation

5. Assimilation

6. Egestion


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Ingestion

It is the Process of takingfood into the body.

We take in food through

the mouth; we chew thefood to form a bolus.

The bolus is swallowed

and moved by peristalsis.


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Peristalsis

It is a wave like

muscle that

contracts to pushfood down the

esophagus and the

small intestine


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Digestion begins in the mouth

Mechanical digestion

It is the process of

breaking down foodphysically.

Food is then convertedmechanically and

chemically fromcomplex to simple statein bolus form.


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Mechanical digestion


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Digestion

Fig. 41.16

Peristalsis (rhythmic contractions) carries the bolusto the stomach


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absorption

Nutrients are absorbed as monomers by the cellslining the gut.

Translocation/ transport

the blood transports the nutrients to all the

parts of the body.

Assimilation

Nutrients are removed from the blood by the

cells by diffusion and active transport, to buildsubstances like proteins for nuclear material andcell membranes and also to replace damagedcells and organelles.


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Egestion

Undigested food is passed out of the body, by

a process called defecation


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Summary

Ingestion

Egestion


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Lifestyle and energy relationships

Please refer to module 1 unit 2


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Energy Pyramids

Only about10% of energypassed onbetweentrophic levels

Few Carnivores

More Herbivores

All supported

by energyfromproducers

Most is lostthrough theorganismslivingprocesses

F d Ch i


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Phytoplankton

Zooplankton

Fish

Shark

Label the trophic levels as herbivore, carnivore, producer,top predator. Indicate which are consumers.

Top Predator

Carnivore

Herbivore

Producer

ConsumersFood Chain


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Lifestyle of herbivores

They have much competition for food so they

developed different feeding habits.

Some are grazers and they feed on grass

E.g. Cow, sheep,....


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Herbivore lifestyle

Browsers eat foliage from trees and shrubs

Examples will be animals like elephants and

giraffes.


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Type of food

Plants foliage

Roots

Underground stems Seeds

And fruits


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Type of teeth

They have well developed molars andpremolars to grind plant matter well.

Jaws can be moved sideways to enable

grinding process.


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Stomach

More than 1 stomach to digest cellulose.

Mutualistic bacteria produce their enzyme

cellulase for digestion of the cellulose in

plants.

Eg. Cow has four chambers or so called

stomach


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Energy relationship

Primary consumers; must consume large

amounts of plant material to meet their

energy requirements.


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Carnivores lifestyle

They are commonly predator and scavengers.

Predators hunt for prey, catch them and then eat

them.

Examples will be lions, snake, spider,


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Scavengers

They feed on dead bodies.

Once the predator have eaten their fill,

scavengers will eat the remainders or the

carcass.

Examples: vultures, hyenas, vultures,


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Type of food

Flesh of other animals

Blood

And bones


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Type of teeth

Well developed canines to rip flesh.

Have carnassials teeth to crush and chew

bones


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Carnivore Teeth Adaptation


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Stomach

Well developed stomach with gastric juice

that enables the digestion of proteins and

bones.


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Energy relationship

Secondary consumers feed on primary

consumers

They require less volume of food because

their diet is rich in proteins.


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Omnivores lifestyle

They feed on plants and animals

Eg: we as human beings, feed on plants

and animals.

In some cases omnivores are predators andhunt for prey.

Omnivores generally live in group and

share their food Why?


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Omnivore

Eats a mixture of plants andanimals e.g. Pigs, humans

Increased chance of survivalas they are not restricted toone diet.

In some cases omnivores arepredators and hunt for prey.

Omnivores generally live ingroup and share their food

Why?


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Type of food

Plant leaves

Vegetables

Fruits

Nuts

Eggs

And meat


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Type of teeth Teeth help in (mechanical

breakdown) of food. Teeth are similar shape and

size, incisors, canines,premolars and molars

Incisors are used forcutting.

Canines are used forpiercing and holding.

Molars have large surfacearea and are used forgrinding.


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Stomach

They have well-developed stomach with

gastric juice to digest proteins and fats.


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Energy relationship

Tertiary consumers; consume least amount of

food as their diet is rich in all the nutrients

that their body need.

Especially proteins.


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Omnivore

Eats a mixture of plants

and animals

E.g. Pigs, humans

Increased chance of

survival as they are not

restricted to one diet.

Digestive Systems are Adapted to their


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Vertebrate dentition generally matches the diet

Digestive Systems are Adapted to theirOwners Lifestyles

Fig. 41.26

An adult human has 32 teeth:

Incisors for cutting

Canines for tearing

Premolars and molars for crushing and'grinding


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Summary of previous lesson

1. Humans, like most animals, are HETEROTROPHS; Weeat other organisms for Food and Energy.

2. FOOD CONTAINS NUTRIENTS, OR MOLECULES THATPROVIDE ENERGY AND MATERIAL FOR GROWTH ANDREPAIR.

3. NUTRIENTS ARE CHEMICAL SUBSTANCES NEEDED BYTHE BODY FOR GROWTH, REPAIR, ANDMAINTENANCE.


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Summary of previous lesson

4. All the different FOODS in the world CONTAIN at least ONE

ofSIX KINDS OF NUTRIENTS: CARBOHYDRATES, PROTEINS,

LIPIDS (FATS), VITAMINS, MINERALS AND WATER.

5. FOUR of these Nutrients- Carbohydrates, Proteins, Fats, and

Vitamins-are ORGANIC COMPOUNDS Because they contain

the Elements Carbon, Hydrogen, and Oxygen.

6. The TWO Remaining Nutrients-Minerals and Water-are

INORGANIC COMPOUNDS

Fig. 5-8

C ll lCell walls


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Glucose

monomer

Cellulosemolecules

Microfibril

Cellulosemicrofibrilsin a plantcell wall

0.5 m

10 m


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Enzymes that digest starch by hydrolyzing linkages cant hydrolyze linkages in cellulose

Cellulose in human food passes through the

digestive tract as insoluble fiber

Some microbes use enzymes to digest cellulose

Many herbivores, from cows to termites, have

symbiotic relationships with these microbes

Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 5-9


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Mechanical and Chemical

digestion

Mr. Khoza


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Introduction

Digestion can be divided into 2 processes:

mechanical and chemical breakdown of the

'insoluble, complex molecules that can be

absorbed.


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Mechanical process

This process physically breaks the food to

increase the surface area for enzyme action.

Enzymes are proteins that catalyze (i.e.,

increase the rates of) chemical reactions.

it also serves to move and mix the food.
http://en.wikipedia.org/wiki/Proteinhttp://en.wikipedia.org/wiki/Catalysishttp://en.wikipedia.org/wiki/Reaction_ratehttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Reaction_ratehttp://en.wikipedia.org/wiki/Catalysishttp://en.wikipedia.org/wiki/Protein


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The mechanical process involves:

Chewing of food (mastication)

Bolus formation which involves saliva andtongue

Peristalsis where muscle action moves thefood along the alimentary canal (tube).

The churning movement of the stomach to

mix the chyme (food + enzymes) Segmentation in the small intestine to mix the

chyme and move it along the canal.


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Roughage

Is very important to the mechanical process.

It help to:

Speed up the movement of food in the digestive

tract (area).Stimulate peristalsis in the colon.

Decrease the occurrence of haemorrhoids andconstipation

Absorb water and makes the contents bulky(large)


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Chemical process

Enzymes break complex nutrients down into

their monomer state (simple molecules) so

that absorption into the blood can take place.

Compounds are hydrolysed as follows:

Carbohydrates- glucose, fructose and

galactose.

Proteins amino acids

Lipids fatty acids and gycerol


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Chemical process

Digestive juices like hydrochloric acid (in the

stomach)and bile (produced by the liver) help

the enzymes to function optimally.


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The Digestive System


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The Digestive System

Mouth

Oesophagus (peristalysis)

Stomach

Small Intestine (jejenum)

Liver

Large Intestine

Gall Bladder

Pancreas

Rectum

Anus

Lets find out what happened to your breakfast today!

(Breaking food down into smaller pieces)


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Oesophagus

Approximately 25cm

long

Moves food from the

throat to the stomach

Muscle movement called

peristalsis

If acid from the stomachgets in here thats

heartburn.


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Stomach

Stores the food you eat

Chemically breaks it

down into tiny pieces Mixes food with

digestive juices

Acid chyme -(pH 2,8) inthe stomach kills

bacteria


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Small Intestine

Small intestines areroughly 6 metres long.

Enzymes and bile are

added. Villi increase the surface

area to help absorbtion.

Nutrients from the foodpass into the bloodstreamthrough the smallintestine walls.


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Liver

Directly affectsdigestion byproducing bile Bile is an enzyme that

helps dissolve fat Processes nutrients in

the blood, filters outtoxins and waste.

Is often called thebodys energy factory


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Gall Bladder

Stores bile from

the liver

Delivers bile whenfood is digested


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Pancreas

Producescompounds to

digest fats and

proteins Neutralizes acids

that enter small

intestine Regulates blood

sugar by producing

insulin


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Large Intestine

About 1.5 metres long

Accepts what smallintestines dont absorb.

Absorbs water andminerals from the wastematter.

Absorption meanstaking into the body viathe blood stream.


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Rectum and Anus

Rectum

About 15cm long

Stores wastebefore egestion.

Anus

Muscular ring that

controls egestion.

Write the name of each


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Write the name of each

colored organ:

Green:

Red:

Pink:

Brown:

Purple:

Green:

Yellow:


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Answers

Green: Oesophagus

Red: Stomach

Pink: Small Intestine

Brown: Large

Intestine

Purple: Liver

Green: Gall Bladder

Yellow: Pancreas


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Humans have 4 types of teeth:

Incisors to cut thefood

Canines to tear the

foodPremolars to grind

and crush the food

Molars to grind andcrush the food.


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Teeth

Mammals have two sets of teeth:Milk teeth in children (22 teeth)

Permanent teeth in adults (32 teeth).

The process of chewing the food is called

mastication.

In humans, the dental formula is calculated on


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half of the jaw, left or right side of the mouth.

The formula is:

2 . 1 . 2 . 3--------left jaw

2 . 1 . 2 . 3---------right jaw

Human(adult)

I -2/2 C -1/1 P 2/2 M 3/3 = 16 X 2 = 32

This indicates: 2 Incisors, 1 Canine,2 Premolars

and 3 Molars on 1 side the top jaw and thesame for the bottom jaw.

life sciences lesson 1 & 2

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